So I said before when we were talking about single atoms, we always define the zero energy as when an electron was actually ejected, but now, when we talk about chemical reactions taking place, it's very, very rare that we're actually going to be talking about anything that gets to this point here.

我之前说过，当我们讨论单个原子的时候，我们总是把零点能,定在电子被发射出去以后，但是现在，当我们讨论化学反应发生的时候，非常非常罕见出现，确实达到,这种程度的情况。

麻省理工公开课 - 化学原理课程节选

So, for example, when people, and we'll talk about this next class, were looking at different characteristics spectra of different atoms, what they were seeing is that it appeared to be these very discreet lines that were allowed or not allowed for the different atoms to emit, but they had no way to explain this using classical physics.

举个例子，当大家看到,不同原子的特征光谱时,他们看到的是一些分离的线,那可以使不同的原子,发射或不发射出去，但是这些无法用经典物理来解释。

麻省理工公开课 - 化学原理课程节选